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Hibernate example source code file (SelectLockingStrategy.java)

This example Hibernate source code file (SelectLockingStrategy.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Hibernate tags/keywords

io, jdbc, jdbcexception, lockoptions, object, object, resultset, selectlockingstrategy, serializable, sessionfactoryimplementor, sessionfactoryimplementor, simpleselect, simpleselect, sql, staleobjectstateexception, string, string

The Hibernate SelectLockingStrategy.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.dialect.lock;
import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.hibernate.JDBCException;
import org.hibernate.LockMode;
import org.hibernate.LockOptions;
import org.hibernate.StaleObjectStateException;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.persister.entity.Lockable;
import org.hibernate.pretty.MessageHelper;
import org.hibernate.sql.SimpleSelect;

/**
 * A locking strategy where the locks are obtained through select statements.
 * <p/>
 * For non-read locks, this is achieved through the Dialect's specific
 * SELECT ... FOR UPDATE syntax.
 *
 * @see org.hibernate.dialect.Dialect#getForUpdateString(org.hibernate.LockMode)
 * @see org.hibernate.dialect.Dialect#appendLockHint(org.hibernate.LockMode, String)
 * @since 3.2
 *
 * @author Steve Ebersole
 */
public class SelectLockingStrategy extends AbstractSelectLockingStrategy {
	/**
	 * Construct a locking strategy based on SQL SELECT statements.
	 *
	 * @param lockable The metadata for the entity to be locked.
	 * @param lockMode Indictates the type of lock to be acquired.
	 */
	public SelectLockingStrategy(Lockable lockable, LockMode lockMode) {
		super( lockable, lockMode );
	}

	/**
	 * @see LockingStrategy#lock
	 */
	public void lock(
	        Serializable id,
	        Object version,
	        Object object,
	        int timeout, 
	        SessionImplementor session) throws StaleObjectStateException, JDBCException {
		final String sql = determineSql( timeout );
		SessionFactoryImplementor factory = session.getFactory();
		try {
			PreparedStatement st = session.getTransactionCoordinator().getJdbcCoordinator().getStatementPreparer().prepareStatement( sql );
			try {
				getLockable().getIdentifierType().nullSafeSet( st, id, 1, session );
				if ( getLockable().isVersioned() ) {
					getLockable().getVersionType().nullSafeSet(
							st,
							version,
							getLockable().getIdentifierType().getColumnSpan( factory ) + 1,
							session
					);
				}

				ResultSet rs = st.executeQuery();
				try {
					if ( !rs.next() ) {
						if ( factory.getStatistics().isStatisticsEnabled() ) {
							factory.getStatisticsImplementor()
									.optimisticFailure( getLockable().getEntityName() );
						}
						throw new StaleObjectStateException( getLockable().getEntityName(), id );
					}
				}
				finally {
					rs.close();
				}
			}
			finally {
				st.close();
			}

		}
		catch ( SQLException sqle ) {
			throw session.getFactory().getSQLExceptionHelper().convert(
					sqle,
					"could not lock: " + MessageHelper.infoString( getLockable(), id, session.getFactory() ),
					sql
				);
		}
	}

	protected String generateLockString(int timeout) {
		SessionFactoryImplementor factory = getLockable().getFactory();
		LockOptions lockOptions = new LockOptions( getLockMode() );
		lockOptions.setTimeOut( timeout );
		SimpleSelect select = new SimpleSelect( factory.getDialect() )
				.setLockOptions( lockOptions )
				.setTableName( getLockable().getRootTableName() )
				.addColumn( getLockable().getRootTableIdentifierColumnNames()[0] )
				.addCondition( getLockable().getRootTableIdentifierColumnNames(), "=?" );
		if ( getLockable().isVersioned() ) {
			select.addCondition( getLockable().getVersionColumnName(), "=?" );
		}
		if ( factory.getSettings().isCommentsEnabled() ) {
			select.setComment( getLockMode() + " lock " + getLockable().getEntityName() );
		}
		return select.toStatementString();
	}
}

Other Hibernate examples (source code examples)

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